The purpose of this longitudinal, descriptive study is to examine, for premature infants, patterns and mediators of heart rate variability (HRV) and adaptive feeding behavior through the first 4 post-term months. The study aims are to explore: (a) the pattern of change of infant HRV, infant adaptive feeding behavior, and mother adaptive feeding behavior just before discharge from the special-care nursery and at I and 4 months; (b) examine the mediating effect of the adaptiveness of mothers' feeding behavior on the contribution to HRV and to the adaptiveness of the infant's feeding behavior, of infant biologic condition, and mothers' depressive symptoms; and (c) explore the longitudinal effect of the adaptiveness of mothers' interactive feeding behavior on the adaptiveness of infant feeding behavior and HRV. A convenience sample of 64 premature infants and their mothers will participate in this study. A Holter monitor will be used to collect HRV data, which will be decomposed into parasympathetic components with spectral analysis. Videotaped feeding interactions will be analyzed using the Parent Child Early Relational Assessment. Mothers' depressive symptoms will be assessed with the Center for Epidemiological Studies- Depression Scale. Infant biologic condition will be estimated with the Neonatal Health Index. Regression analysis will be used to address the study aims.